Preparing to support fragment resolution against non-hierarchical schemes

Adds a new GURL::GetContent() to retrieve the text after scheme: specifically
intended for use in non-hierarchical schemes (data: etc).
Doing the first part of https://codereview.chromium.org/23835019/
in a preparation CL.

BUG=291747

Review URL: https://codereview.chromium.org/23549039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230781 0039d316-1c4b-4281-b951-d872f2087c98
[rAC, OSX] Fix keyView handling.

The rAC dialog used to try to restore whatever the previous keyview was
once the loading shield ended - that triggered inadvertently autopopup
messages.

This change removes the firstResponder hack that did this to hide focus
rings and instead does the right thing - hide the underlying dialog
when the shield is showing.

BUG=310724
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/39273003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230782 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230782